Screening of short-and medium-chain chlorinated paraf?ns in selected riverine sediments and sludge from the Czech Republic
Petra Pr
ˇibylova ′,Jana Kla ′nova ′*,Ivan Holoubek RECETOX d Research Centre for Environmental Chemistry and Ecotoxicology,Masaryk University,Kamenice 3/126,62500Brno,Czech Republic Received 13July 2005;received in revised form 11November 2005;accepted 11December 2005
Data on contamination of sediments from industrial areas ?ll the informational gap in the
?eld of contamination of the Central Europe by chlorinated paraf?ns.
Abstract
Wide distribution of chlorinated paraf?ns in the environment has already been demonstrated in several studies;however,information about their levels in the Central Europe is still very limited.First study focused on the SCCP contamination of the Czech aquatic environment have been performed recently,and its results motivated the authors to analyze sediments from a wide set of the Czech rivers in order to obtain more detailed information.Thirty-six sediment samples from eleven rivers and ?ve drainage vents neighboring the chemical factories were analyzed;special attention was paid to the industrial areas.For the ?rst time in the Czech Republic,medium-chain in addition to short-chain chlorinated paraf?ns were analyzed using GC-ECNI-MS.Chlorinated paraf?ns were detected in sediment samples on the concentration levels up to 347ng g ?1for short-chain chlorinated paraf?ns,and 5575ng g ?1for medium-chain chlorinated paraf?ns.Average chlorination degree of SCCPs was 65%.
ó2006Elsevier Ltd.All rights reserved.
Keywords:Chlorinated paraf?ns;Polychlorinated n -alkanes;Sediment;Gas chromatography e electron capture negative ion trap mass spectrometry;Czech Republic
1.Introduction
Chlorinated paraf?ns (CPs)are industrially produced mixtures of compounds with the general formula of C n H 2n t2?z Cl z .Based on the chain length,they are classi?ed into three categories:short-chain (C 10e C 13;SCCPs),medium-chain (C 14e C 17;MCCPs),and long-chain (C >17;LCCPs)chlorinated analogs of the straight-chain alkanes from which they are manufactured (Tomy et al.,1998).They can be further categorized according to the degree of chlorination:40e 50%,50e 60%,and 60e 70%.Chlorinated paraf?ns have various
industrial applications:they are used in sealants,paints,metal-working ?uids,leather treatment chemicals,carbon-less copy paper,as ?ame retardants or softeners in rubbers,textiles,polyvinylchloride (PVC)or other polymers (UNECE ad hoc Expert Group on POPs,2003;Euro Chlor,2006).SCCP mixtures with high chlorine content (60e 70%in weight)are mostly used as ?ame-retardants.MCCPs,which usually do not reach such a high chlorination degree,are mainly used as softeners (plasticizers)while retaining an ad-vantage of ?ame retarding properties (Euro Chlor,2006).The use of SCCPs in European Union decreased in the 1990s,and the estimated production is now lower than 15,000tonnes per year (Ospar Commission,2001).On the contrary,production of MCCPs has a growing trend in Europe,and it ranges from 45,000to 160,000tonnes per year (Euro-pean Environmental Agency,2002).In 2002,32,000tonnes
*Corresponding author.Tel.:t420549495149;fax:t420549492840.
E-mail addresses:pribylova@recetox.muni.cz (P.Pr
ˇibylova ′),klanova@recetox.muni.cz (J.Kla
′nova ′),holoubek@recetox.muni.cz (I.Holoubek).0269-7491/$-see front matter ó2006Elsevier Ltd.All rights reserved.
doi:10.1016/j.envpol.2005.12.020
Environmental Pollution 144(2006)248e
254
of MCCPs was used just for PVC production in the European Union,while only1000tonnes of SCCPs was used as sealants, adhesives,softeners or?ame-retardants in rubber and textiles industries(Euro Chlor,2006).In Central Europe,short-and medium-chain chlorinated paraf?ns are still produced in the Slovak Republic(Novacke chemicke zavody),where dodeca-nes,pentadecanes,and pentacosane with chlorination degree between40%and64%are produced.
Chlorinated paraf?ns have a very low acute toxicity,they are classi?ed as category3carcinogens,and they are consid-ered to be toxic for aquatic environment.MCCPs have not yet been classi?ed according to the Dangerous Substances Directive(67/548/EEC);however,they have recently been proposed for a new classi?cation as dangerous for the environ-ment,and the category3carcinogens(Euro Chlor,2006).
Chlorinated paraf?ns could reach the environment through production,storage,transportation or industrial use,and also by leaching,runoff and volatilization from contaminated envi-
ronmental compartments.There have been several studies fo-cused on the CP contamination of sediments around the globe. Data from United Kingdom showed heavy contamination of sediments by short-and medium-chain CPs;the sum of MCCPs found in sediment was up to65m g g?1(Nicholls et al.,2001).SCCP levels in sediments from Norway were de-termined to be19m g g?1of the wet weight,and MCCP levels up to11m g g?1of the wet weight(Borgen et al.,2003).In Jap-anese sediments concentrations of CPs(CP10e30)were up to 10m g g?1.In other countries,contamination of freshwater sediment was generally lower:MCCP levels lower than 5ng g?1were measured in Lake Zu¨rich,Switzerland,and they stayed bellow700ng g?1in the River Lech,Germany (Tomy et al.,1998).CP concentrations in sediments from Lake Fox,Canada were up to257ng g?1(Tomy et al., 1998,1999),in sediments from Lake Ontario researchers found the average SCCP concentration of49ng g?1(Marvin et al.,2003),and1e11ng g?1of CPs were detected in Sugar Creek,USA.For the sea sediments,112ng g?1of SCCPs and 146ng g?1of MCCPs were found in German Bight,North Sea (Hu¨ttig et al.,2004),and highest concentrations in Baltic Sea sediments reached377and499ng g?1for SCCPs and MCCPs,respectively(Hu¨ttig et al.,2004).Concentration levels up to65m g g?1were measured in sewage sludge from industrial areas in Germany;while30m g g?1was the CP concentration in sewage sludge from Switzerland.Also, the samples from drainage ditches of a CP manufacturing fa-cility in the USA showed concentrations up to40m g g?1for SCCPs and50m g g?1for MCCPs(Table1).
In spite of the fact that short-and medium-chain chlori-nated paraf?ns are still manufactured in Slovakia,there is a lack of data about CP contamination of the Central European environment.There has only been one paper focused on two industrial areas in the Czech Republic with the aim of deter-mining whether the contamination of aquatic environment by short-chain chlorinated paraf?ns(SCCPs)is an issue de-serving more attention(Sˇtejnarova′et al.,2005).The highest concentration of SCCPs was detected in sediment from Drev-nice river,Zlin region(up to181ng g?1of dry sediment weight).Results of the study as well as the recent regulation of the Czech government concerning monitoring of SCCPs in aquatic ecosystem motivated the authors to perform the here presented screening study of sediment samples from all bigger Czech rivers.
2.Materials and methods
2.1.Chemicals
n-Hexane(Supersolv;Merck,Darmstadt,Germany),tetrahydrofuran,di-chloromethane(Pestiscan;Labscan,Dublin,Ireland),sulfuric acid(Pro analy-sis;Merck,Darmstadt,Germany),hydrochloric acid(Pro analysis;Lachema, Brno,Czech Republic)were used as received.Powder copper(Fluka,Seelze, Germany)was activated before application by addition of hydrochloric acid, and washed with deionized water.Silica gel(63e200mesh,Merck,Darm-stadt,Germany)was cleaned by dichloromethane for8h,activated at 150 C for12h,and deactivated by addition of3%(w/w)deionized water.He-lium and nitrogen in5.5quality were supplied by Siad(Branˇany u Mostu, Czech Republic).Methane in5.5quality was supplied by Linde(Brno,Czech Republic).Standards of chlorinated paraf?ns d SCCPs with various chain lengths(CP10,11,12,13)and chlorination degree of each chain(45%,50%, 55%,60%,65%,70%)d and MCCPs(CP14.47;CP16.50;CP17.46)were synthe-sized,and kindly provided by the group of Professor Dr.H.Parlar,Technical University of Munich(Germany).Synthesis of chlorinated paraf?ns was de-scribed elsewhere(Coelhan et al.,2000).Cereclor63L(technical mixture CP10e13.63)was supplied by Imperial Chemicals(UK).Lindane was used as an internal standard(Supelco,Bellefonte,PA,USA).
2.2.Instrumentation
A centrifuge Jouan BR4(Jouan Technology for life,Winchester,V A, USA)was used.Chromatographic separation was carried out on a gas chro-matograph Finnigan Q-GC connected with a Finnigan GCQ mass spectrometer (Thermo Electron,San Jose,CA,USA).A gas chromatograph was equipped with a split/splitless injector(Finnigan2200)and a silica capillary column (30m,0.25mm i.d.)coated with0.25m m?lm of DB5-MS stationary phase (5%phenyl/95%methylpolysiloxane,J&W Scienti?c,Folsom,CA,USA).
2.3.Samples
Sediment samples from11rivers(Labe,Bilina,Ohre,Vltava,Jihlava, Dyje,Svitava,Morava,Becva,Mala Becva,and Drevnice),and?ve drainage vents in the Czech Republic were taken.Sampling sites were selected with Table1
Chlorinated paraf?ns in the sediment and sludge samples
Country Concentration in
sediment/sludge
(m g g?1)
P
MCCPs
P
CPs
P
SCCPs
United Kingdom65
Germany(sludge)65
Germany(River Lech)0.7
German Bight,North See0.1120.146
Baltic Sea0.3770.499
Switzerland(sludge)30 Switzerland(Lake Zurich)0.005
Norway1911
Japanese10 USA(sludge)4050
USA(Sugar Creek)0.011 Canada(Lake Fox)0.257 Canada(Lake Ontario)0.049
249
P.Prˇibylova′et al./Environmental Pollution144(2006)248e254
a special attention to potential industrial sources of contamination.Details about the sampling sites are given in Fig.2and Table2.Top-layer (<10cm)sediment was sampled by dredging during several sampling cam-paigns in2003and2004(see Table2).Samples were transported to the labo-ratory in glass boxes and air-dried at the room temperature.Dry samples were homogenized and total organic carbon was determined in each sample.
2.4.Extraction and clean-up
Ten grams of dry sediment sample was extracted by hot solvent extraction (Soxtec-Bu¨chi,Switzerland)with dichloromethane(120ml)for60min.Inter-fering compounds were removed by addition of sulfuric acid(3ml):extracts changed to hexane were heated with sulfuric acid addition(in the oven at 60 C,60min)and centrifuged.After centrifugation at1500rpm for5min, the hexane fraction was taken and evaporated to500m L with a nitrogen stream.Activated copper was used for sulfur removal.A glass column (30cm length,1cm i.d.)?lled with5g of silica gel(activated overnight at 150 C,and deactivated by addition of3%w/w of deionized water)was used for fractionation.The?rst fraction was eluted by n-hexane(40ml),the second(CPs containing)fraction by DCM:n-hexane(1:1)(30ml).Clean-up procedure was described in detail elsewhere(Sˇtejnarova′et al.,2005).g-HCH as an internal standard was added to all samples before analysis on gas chromatography-electron capture negative ion trap mass spectrometry (GC-ECNI-IT-MS)to get the?nal concentration of2ng m L?1.
2.5.Gas chromatography and mass spectrometry
CPs were determined in sample extracts using gas chromatography with mass spectrometric detection working in electron capture negative ionization mode(GC-ECNI-MS)on a Thermo Electron GCQ benchtop ion trap instru-ment.Chromatographic separation was achieved on a gas chromatograph Fin-nigan Q-GC with a capillary column(DB5-MS,30m?0.25mm?0.25m m) and following parameters of chromatographic separation:splitless injection, injector temperature250 C,injection volume1m l,He at a constant linear ve-locity of36cm s?1;temperature program started at100 C,held for1min., raised at30 C min?1to160 C,held for5min,raised at30 C min?1to 310 C,?nal hold time22min.Total time of analyses was35min.
Methane was used as a reagent gas for an ion trap GCQ.Full spectra were taken under the full scan conditions in the mass range of240e550amu.Neg-ative mode chemical ionization was optimized to give the highest response for the peak m/z414of the internal calibration compound[FC-43,per?uorotribu-tylamine].The electron beam energy was70eV.Transfer line temperature was 275 C and ion source temperature was200 C.Lenses were auto tuned to12, 125,and16V for lens1,lens2,and lens3,respectively.The trap offset was set manually to7.0V.
This method is capable of distinguishing between short-and medium-chain chlorinated paraf?ns in one sample,since the retention times are evaluated as an important parameter enabling the SCCP and MCCP identi?cation.How-ever,the complete separation is not possible.Typical chromatogram of CPs is shown in Fig.1.Due to the small differences in the mass between some SCCP and MCCP fragments,only a limited number of ions were selected for the quanti?cation of each group of equal chain length(Sˇtejnarova′et al., 2005):313/381/417(C10),329/361/395(C11),341/375/409(C12),355/389/ 423(C13),403/439/471(C14),383/417/451/489(C15),and465/499/535 (C16).Interference of some SCCP and MCCP masses had to be taken into con-sideration(Reth and Oehme,2004).The masses of chlorinated undecanes (395/431/465),for instance,interfere in spectra with those of chlorinated hex-adecanes.Similarly,the masses of chlorinated decanes interfere with those of chlorinated pentadecanes.
The standard closely matching the?ngerprint of a real contaminant present in the sample was selected for quanti?cation of each carbon chain(standards CP10,CP11,CP12,CP13with45%,50%,55%,60%,65%,70%chlorination degree,and CP14.47,CP15.50,CP16.46were available for SCCPs and MCCPs, respectively).In case of the Czech river sediments,the standards CP10.65, CP11.65,CP12.65,and CP13.65were applied since the average percentage of chlorination of SCCPs present in the river sediment samples was determined to be65%.Medium-chain chlorinated paraf?ns were quanti?ed using the only available standards CP14.47,CP15.50,and CP16.46.
2.6.Quality assurance and quality control
Surrogate recoveries of the analytical procedure(including extraction,sul-furic acid treatment,and adsorption column chromatography)were performed by analysis of CP free sediment samples enriched with Cereclor63L and MCCP mixture to get the?nal concentration of1000and100ng g?1(dry weight).Recoveries were determined to be103?8%(n?12)for low,and 92?11%(n?5)for high concentration of SCCPs.Recoveries for MCCPs after the same procedures were57?3%(n?4)for low,and68?4% (n?4)for high concentration.
The detector response was linear in the tested range of2and 1000ng m L?1,and it depended on a chlorination degree and a chain length in case of chlorinated paraf?ns.Five-point calibration was prepared using in-dividual mixtures of SCCPs and MCCPs in the concentration range of2and 500ng m L?1.Linear regression con?dence values R2varied from0.951for CP10.65to0.9983for CP13.65.The analytical detection limit for the sum of CPs was2ng m L?1.The signal to noise quanti?cation ratio was set to be higher than10.The limit of quanti?cation for the real sediment samples was based on the lowest concentration of CPs that could be calculated.The limit of quanti?cation for the sediment samples was10ng g?1(dry weight). Laboratory blanks were analyzed(one with each10real samples),and they gave no signal that could interfere with CP detection.Repeatability of the GC-MS measurement was tested.Relative standard deviation was calculated to be6%(n?10).
3.Results and discussion
The Czech Republic has historically been highly industrial-ized country with coal mining,metalworking,engineering, chemical,rubber,textile and other industries.In the1990s, production was restricted in many branches,but there are still several environmentally stressed regions with a high concen-tration of industry.Sediment samples from Ohre(sampling sites no.10e12,Table2,Fig.2),and Bilina(6e9)rivers were collected in northwestern part of the country with biggest chemical companies(Chemopetrol Zaluzi,Spolchemie Usti, Eastman Sokolov).In addition to the river sediments,several sewage sludge samples were taken from drainage vents of Chemopetrol(8),and Spolchemie(33e36)companies.Sedi-ments from Labe(1e5),and Vltava(13)rivers were sampled in the central part of the country where chemical company Spolana Neratovice is considered to be the most serious point source of contamination besides some engineering companies. Metalworking,engineering,chemical,rubber,leather,and paint industries dominate in the eastern part of the country. Morava river(19e27)with its tributaries Becva(28e30), Mala Becva(31),Drevnice(32),and Dyje(15e17)are the main water bodies of this region,and they were all included in the sampling design of the study.
Chemopetrol Zaluzi(8)was selected to be one of the sites where the sludge was analyzed since this company is the main producer of ethylene(supplied to Spolana Neratovice,where PVC is manufactured),and propylene(supplied to Eastmen Sokolov)in the country.However,there were no CPs detected in the sewage sludge from Chemopetrol.On the contrary,the CP levels in the sludge from Spolchemie Usti(33e36) ranged from205ng g?1to396ng g?1,and from736ng g?1 to2301ng g?1for SCCPs and MCCPs,respectively.In
250P.Prˇibylova′et al./Environmental Pollution144(2006)248e254
Spolchemie,organic paints and pigments are produced,and
application of CPs as adhesives can be a source of signi?cant contamination of the sludge.Relatively high concentrations of SCCPs (up to one third of the sum of CPs,Table 2)support this assumption.
Short-and medium-chain chlorinated paraf?ns were de-tected in several sediment samples as well;all studied rivers except for Jihlava (14),Svitava (19),and Vltava (13)were contaminated at least at some of the sampling sites (Table 2).Ohre river (northwest)on its upper stream in Kynsperk (10)was the most contaminated site in this study,with SCCP concentration of 89ng g ?1but that of MCCPs as high
as 5575ng g ?1.This sampling site was probably strongly af-fected by a local factory (GPH,a Nexans company)where a range of crimping connectors and lugs for aluminum or cop-per cables are produced.A sale and service of hydraulic and mechanic equipments for electrical engineering was con?rmed at the same facility as well.Metal working and hydraulic ?uids could increase the CP contamination of Ohre river as well.East-men Sokolov,the chemical factory where waterbased disper-sions and polymers are produced,is located down the same river (Ohre).Two sampling sites up (11)and down (12)the stream from this company have not shown such a heavy con-tamination (14ng g ?1and 32ng g ?1for SCCPs,307ng g ?
1
Fig.1.Chromatogram of CPs from the sediment
sample.
Fig.2.Map of the sampling sites showing detected levels of CP contamination.
252P.Pr ˇibylova ′et al./Environmental Pollution 144(2006)248e 254
and600ng g?1for MCCPs,with higher upstream levels).It can be concluded that CPs released to the aquatic ecosystem are quickly bound to the sediment and remain in the close proximity of their source causing signi?cant local contamina-tion.Similar results were obtained for Bilina river:CPs were detected in river sediment in Usti(6)near Spolchemie,where they were also found in high concentrations in the sewage sludge.On the contrary,CPs were not detected in sediments further down the stream of Bilina river in Most(7and9).
The second highest CP concentration was found in sedi-ments from Labe river(central region)in Libis(5)near Spo-lana Neratovice(347ng g?1for SCCPs,1598ng g?1for MCCPs).It is not surprising since PVC production has been known to be a major CP application and a potential source of CP contamination,and Spolana is a main producer of PVC.All the other sediment samples from Labe river(1e4) had low or none concentrations with maximum of12ng g?1 for SCCPs and73ng g?1for MCCPs.
In the eastern part of the country,Drevnice river(a tributary to Morava)with54ng g?1of SCCPs,and892ng g?1of MCCPs in sediment was the most contaminated site probably due to the rubber,leather,and engineering industries.Dyje in Znojmo(28ng g?1of SCCPs,757ng g?1of MCCPs),Becva in Zubri(59ng g?1of SCCPs,120ng g?1of MCCPs),and Mala Becva(3ng g?1of SCCPs,113ng g?1of MCCPs) were other Morava tributaries where CPs were found,but there were just two sites with limited CP contamination found in Morava river itself:Uherske Hradiste(27ng g?1of SCCPs, 416ng g?1of MCCPs,probably due to the long history of the paint industry)and Spytihnev(149ng g?1of SCCPs, 193ng g?1of MCCPs);all the others were CP free.
Medium-chain chlorinated paraf?ns prevailed in all sam-ples,which is in agreement with data demonstrating trends in production and use of SCCPs and MCCPs.In most of the sampling sites,MCCP levels were more than one order of magnitude higher than those of SCCPs(Table2).
Highest concentration of SCCPs was found in the sewage sludge from Spolchemie Usti(205e396ng g?1);a similar level was detected in Libis drain(347ng g?1)near Spolana Neratovice.This probably indicates the use of SCCPs as adhe-sives in paints,as softeners or?ame retardants in polymer pro-duction.Levels of MCCPs in these samples were only2e5 times higher than those of SCCPs.In the remaining samples, SCCPs were detected in tens of nanograms per gram only, while concentrations of MCCPs were1e2orders of magni-tude higher.In all samples,chlorinated undecanes and tride-canes were the most abundant molecules in the SCCP mixture(Table2).The average chlorination degree of short-chain chlorinated paraf?ns was65%in all collected samples.
Medium-chain chlorinated paraf?ns were found in hun-dreds of nanograms per gram of sediment in most of the sites. However,in the sediment from Ohre river in Kynsperk,their level reached5575ng g?1and was higher than in any sewage sludge(804e2301ng g?1in Spolchemie Usti).MCCP con-centration in this sample was60times higher than the concen-tration of SCCPs.Medium-chain chlorinated paraf?n concentration varied between18and5575ng g?1,and chlori-nated hexadecanes were the most abundant.
Polychlorinated biphenyls(PCBs),organochlorinated pesti-cides(OCPs),and polyaromatic hydrocarbons(PAHs)were determined in most of the samples from this study as well. PCBs ranged between7and134ng g?1,DDTs between2 and43ng g?1,HCHs between0.5and11ng g?1,and PAHs between2and66m g g?1.There was no correlation observed between these persistent organic pollutants and detected CP levels.On the contrary,neither the sample with highest PCB (134ng g?1)or highest PAH(66m g g?1)levels(both from Bi-lina river)showed any CP contamination.Similarly,the sites with highest levels of CPs in sediment showed only very low PCB,OCP or PAH concentrations.
Total organic carbon was measured in all sediment samples. No signi?cant correlation between the organic carbon content and CP concentration in the sediment was found using Spear-man correlation analysis.The sewage sludge samples were ex-cluded from the statistical analysis.
4.Conclusion
Results from GC-ECNI-IT-MS analysis of36sediments from11Czech rivers con?rmed the assumption that chlori-nated paraf?ns are widely distributed in the Czech aquatic en-vironment.The highest concentrations of chlorinated paraf?ns were detected in river sediments close to the chemical and electro engineering industries(GPH,a Nexans company, Kynsperk,Spolana Neratovice,Spolchemie Usti).Detected maxima up to2698ng g?1for the sum of CPs in the sewage sludge,and5664ng g?1for the sum of CPs in river sediments correspond to the data about the CP contamination of Euro-pean rivers published recently.
Medium-chain chlorinated paraf?ns highly prevailed in all samples,which is in agreement with the known trends in pro-duction and use of SCCPs and MCCPs,but in contrast with other data previously published.There have only been very few papers concerned with both,SCCP and MCCP concentra-tions in sediments;according to available data,however,their levels were comparable.It is obvious that MCCP/SCCP ratio is source speci?c and cannot be simply correlated with a level of contamination or a distance from the source.Both low and high ratios were found in contaminated areas close to the sour-ces as well as in remote areas.More detailed study with a row of samples along the river with various point sources is obvi-ously needed to evaluate the changes in ratio,and to estimate the mobility of SCCPs and MCCPs in aquatic environment. This is a subject of our future work.
This project has been carried out as a contribution to the ongoing national POPs inventory in the Czech Republic, which is focused on the new types of persistent industrial substances.
Acknowledgements
The authors would like to thank Professor Parlar,Technical University of Munich,Germany,for providing standards of
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P.Prˇibylova′et al./Environmental Pollution144(2006)248e254
chlorinated paraf?n.This work was supported by the Ministry of Education,Youth and Sports(MSM0021622412). References
Borgen,A.R.,Schlabach,M.,Mariussen,E.,2003.Screening of chlorinated paraf?ns in https://www.doczj.com/doc/3813571526.html,anohalogen Compound60,331e334. Coelhan,M.,Saraci,M.,Parlar,H.,2000.A comparative study of polychlori-nated alkanes as standards for the determination of C10-C13polychlori-nated paraf?ns in?sh samples.Chemosphere40,685e689.
Chlorine online information resource.
Hu¨ttig,J.,Zencak,Z.,Oehme,M.,2004.Levels of chlorinated paraf?ns in North and Baltic Sea https://www.doczj.com/doc/3813571526.html,anohalogen Compound66,1344e 1349.
Marvin, C.H.,Painter,S.,Tomy,G.T.,Stern,G.A.,Braekevelt, E., Muir,D.C.G.,2003.Spatial and temporal trends in short-chain chlorinated paraf?ns in Lake Ontario sediments.Environmental Science and Technol-ogy37,4561e4568.Nicholls,C.R.,Allchin,C.R.,Law,R.J.,2001.Levels of short-and medium-chain length polychlorinated n-alkanes in environmental samples from se-lected industrial areas in England and Wales.Environmental Pollution114, 415e430.
Ospar Commission,2001.Short chain chlorinated paraf?ns.
Reth,M.,Oehme,M.,2004.Limitations of low resolution mass spectrometry in the electron capture negative ionization mode for the analysis of short-and medium-chain chlorinated paraf?ns.Analytical and Bioanalytical Chemistry378,1741e1747.
Sˇtejnarova′,P.,Coelhan,M.,Kostrhounova′,R.,Parlar,H.,Holoubek,I.,2005.
Analysis of short-chain chlorinated paraf?ns in sediment samples from the Czech Republic by short-column GC/ECNI-MS.Chemosphere58,253e 262.
Tomy,G.T.,Fisk,A.T.,Westmore,J.B.,Muir,D.C.G.,1998.Environmental chemistry and toxicology of polychlorinated n-alkanes.Review of Envi-ronmental Contamination and Toxicology158,53e128.
Tomy,G.T.,Stern,G.A.,Lockhart,W.L.,Muir,D.C.G.,1999.Occurrence of C10-C13polychlorinated n-alkanes in Canadian midlatitude and arctic lake sediments.Environmental Science and Technology33,2858e2863. UNECE ad hoc Expert Group on POPs,2003.Short chain chlorinated paraf-?ns(SCCP)Substance Dossier.Final Draft II,1e133.
254P.Prˇibylova′et al./Environmental Pollution144(2006)248e254